/*
* Copyright (c) 1990 James Ashton - Sydney University
* Copyright (c) 2012 Stefano Sabatini
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* X-Face common definitions.
*/
#include <stdint.h>
/* define the face size - 48x48x1 */
#define XFACE_WIDTH 48
#define XFACE_HEIGHT 48
#define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT)
/* compressed output uses the full range of printable characters.
* In ASCII these are in a contiguous block so we just need to know
* the first and last. The total number of printables is needed too. */
#define XFACE_FIRST_PRINT '!'
#define XFACE_LAST_PRINT '~'
#define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1)
/*
* Image is encoded as a big integer, using characters from '~' to
* '!', for a total of 94 symbols. In order to express
* 48x48 pixels with the worst case encoding 666 symbols should
* be sufficient.
*/
#define XFACE_MAX_DIGITS 666
#define XFACE_BITSPERWORD 8
#define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD)
#define XFACE_WORDMASK (XFACE_WORDCARRY - 1)
// This must be larger or equal to log256(94^XFACE_MAX_DIGITS)
#define XFACE_MAX_WORDS 546
/* Portable, very large unsigned integer arithmetic is needed.
* Implementation uses arrays of WORDs. */
typedef struct {
int nb_words;
uint8_t words[XFACE_MAX_WORDS];
} BigInt;
/**
* Add a to b storing the result in b.
*/
void ff_big_add(BigInt *b, uint8_t a);
/**
* Divide b by a storing the result in b and the remainder in the word
* pointed to by r.
*/
void ff_big_div(BigInt *b, uint8_t a, uint8_t *r);
/**
* Multiply a by b storing the result in b.
*/
void ff_big_mul(BigInt *b, uint8_t a);
/* Each face is encoded using 9 octrees of 16x16 each. Each level of the
* trees has varying probabilities of being white, grey or black.
* The table below is based on sampling many faces */
enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE };
/* Data of varying probabilities are encoded by a value in the range 0 - 255.
* The probability of the data determines the range of possible encodings.
* Offset gives the first possible encoding of the range. */
typedef struct {
uint8_t range;
uint8_t offset;
} ProbRange;
extern const ProbRange ff_xface_probranges_per_level[4][3];
extern const ProbRange ff_xface_probranges_2x2[16];
void ff_xface_generate_face(uint8_t *dst, uint8_t * const src);